The present invention relates generally to a filtering apparatus for removing lint and small debris from the air drawn through a vacuum cleaner. More particularly, the invention is directed to a final filter for cleaning the cooling air drawn into a motor driven pump of a vacuum cleaner featuring a centrifugal separator.
Vacuum cleaners of the type having a centrifugal separator normally use a motor driven pump to draw air, dirt and debris into the centrifugal separator which deposits particulate material entrained in the air into a receptacle. The air is then drawn from the centrifugal separator and forced through the motor by the pump downstream from the centrifugal separator for the purpose of cooling the motor. When full, the receptacle is removed, the debris dumped out, and the receptacle is replaced in the vacuum cleaner.
While vacuum cleaners featuring a centrifugal separator have certain advantages over those which feature a filter media, such as a filter bag, one disadvantage stems from the use of air discharged from the separator to cool the motor. Certain types of particulates tend to pass through the separator. These may include very fine particles or debris having a high lift-to-weight ratio, such as fine hair. These particles build up in the motor/pump combination and lead to long term reliability and maintenance problems with the vacuum cleaner.